Gaseous electric discharge device



Nov. 12, 1935. s. GAIDIES ETAL 2,020,727

GASEOUS ELECTRIC DISCHARGE DEVICE I Filed March '7, 1932 INVENTORS MW WWATTORNEY Patented Nov. 12, 1935 UNITE STATES PATENT OFFICE 2,020,727GASEOUS ELECTRIC DISCHARGE DEVICE Application March '1, 1932, Serial No.597,376 In Germany March 14, 1931 4; Claims. (01. 176-126) The presentinvention relates to gaseous electric discharge devices generally andmore particularly the invention relates to electrode structures for suchdevices.

It has long been a practice in the art to use cold, sheet-metalelectrodes in electric discharge devices, particularly those used forillumination, which have a gaseous atmosphere comprising gases, orvapors or a gas-vapor mixture. Such electrodes are not capable ofpassing large currents for long operating periods withoutdisintegrating, such disintegration shortens the useful life and lowersthe efficiency of said electrodes. As the rate of disintegrationincreases 5 with the strength of the current it has been necessary,heretofore, to use electrodes of large area even with a comparativelyweak current, such as 100 milliamperes, to avoid a rapid disintegrationof the electrode. material.

3 The object of the present invention is to reduce the rate ofdisintegration of cold, sheet-metal electrodes useful in electricdischarge devices. A further object of the invention is to provide acold, sheet-metal electrode which is more efli- 5 cient and which iscapable of passing greater currents for longer periods of operation thanthose now known in the art. Still further objects and advantagesattaching to the invention and to its use and operation will be apparentto those skilled in the art from the following particular description.

The main cause of disintegration of this type of electrode is the largecathode drop. This cathode drop may be greatly reduced by providl ing inthe container of an electric discharge device an electron emittingmaterial, such as an alkali or an alkali earth, which activates theoperating surfaces of the electrode to substantial y reduce the cathodedrop and therewith the rate ill of disintegration of the sheet metalelectrode. The presence of this activating material in the container ofa gaseous electric discharge device is beneficial to the gaseousatmosphere since itacts as a getter, uniting with any impurities 45therein. According to this invention the new and novel cold, sheet-metalelectrode for electric discharge devices is provided with a chamberhaving a recessed, contracted opening, or a plurality of recessed,contracted openings in the di- 50 rection of the discharge path, and theactivating, electron-emitting material is placed in said chamber. Asteady and permanent supply of activating material in an electrodehaving such a structure is assured since the sputtering and 55dissipation of the electron-emitting material is controlled and reducedto a minimum. Having this structure the electrode is more eflicient thanprevious cold, sheet-metal electrodes of the same size, has a longeruseful operating life and is capable of passing greater currents forlonger 5 operating periods.

In the drawing accompanying and forming part of this specification threeembodiments of the new and novel electrode are shown, in which Fig. l isa side elevational view of an electric l0 discharge device the containerthereof being broken away in the region of the electrode, an embodimentof the new and novel electrode bein shown in cross section,

Fig. 2 is a sectional view oi another embodil5 ment of the invention andFig. 3 is a similar view of still another embodiment of the new andnovel electrode.

Like numbers denote like parts in all the figures.

Referring to Fig. 1 of the drawing l is the container of an electricdischarge device filled with gases, or vapors, or a gas-vapor mixturesuch as neon, nitrogen, mercury, or a mixture of argon and mercury. Thenew and novel cold, sheetmetal electrode is sealed and supported thereinby lead 6. Said electrode comprises a chamber 2, having an open-ended,cone shaped part 5 recessed therein. The inner wall of said chamber 2 iscoated with an electron emitting material such as caseium, sodium,potassium, barium, etc. or, when desired, the activated oxides of thesematerials. The inner wall of said chamber 2 supports the electricdischarge in said electric discharge device when the device is firstplaced into operation, and due to the sputtering of the coating oi theelectron-emitting material on the inner walls 01 said chamber 2 a smallportion of the particles of said sputtered material passes through theopening 4 in said part 5 and deposits onthe outer wall of said part 5 sothat said outer wall is activated and also supports the electricdischarge. Thus even the small, minute portion of the sputteredparticles of electron-emitting material that pass through the opening 4are used on the outer wall of said part 5 and aid in the currentconduction process. Having this structure the electrode has a longoperaclng life since the sputtering and dissipation of the activatingmaterial is controlled by the recessed, contracted opening 4.

In the embodiment shown in Fig. 2 the open, cone shaped part 5 protrudesfrom the chamber 2, the end of greater diameter being in the directionof the discharge path. The inner wall of said part 5 as well as theinner wall of said chamber 2 is coated with electron-emitting materialsimilar to that disclosed in the discussion of Fig. 1. Having thisstructure said part 5 facilitates the starting of the electric dischargein an electric discharge device in which it is used. Openings ment ofthe invention than with that shown in Fig. 1 since a greater activateddischarge supporting surface is available.

In the embodiment of the electrode shown in Fig. 3 a number of circularrecesses 8 are provided in said chamber 2 in the direction of thedischarge path. Each of said recesses 8 has a slit 9 at the bottomthereof, and each of said recesses 8 is a. discharge supporting surface.A small portion of the sputtered particles from the coating 3 ofelectron-emitting material in said chamber 2 pass through said slits 9and stick to the surface of recessed parts 8 to maintain these dischargesupporting surfaces in an activated condition; Stronger currents may beused in connection with this embodiment of the invention than in thatshown in Fig. 2 since a greater area of activated, discharge supportingsurface is available.

In the above described electrode structure the sputtering anddissipation. of the electronemitting, activating material is controlledby the recessed openings in said electrodes so that said material lastsa long time and the discharge supporting surfaces of the electrodes aremaintained in an advantageous condition to the end that greateroperating currents may be used on a device equipped with cold,sheet-metal electrodes than was practical hitherto.

While we have shown and described and have pointed out in the annexedclaims certain novel features of the invention, it will be understoodthat various omissions, substitutions and changes in the forms anddetails of the device illustrated and in its use and operation may bemade by those skilled in the art without departing from the broad spiritand scope of the invention.

What we claim as new and desire to secure 1 by Letters Patent of theUnitedstates is:-

1. An electric discharge device comprising a container, a gaseousatmosphere therein, electrodes sealed therein, one of said electrodesbeing a hollow electrode having a truncated conical 1c part protrudingtherefrom and opening into the interior thereof, the end of greaterdiameter being in the direction of the discharge path, the inner wallsof said conical part and of said electrode being coated withelectron-emitting material.

2. An electric discharge device comprising a container, a gaseousatmosphere therein, electrodes sealed therein, one of said electrodesbeing a hollow electrode having a plurality of circular recesses ofdecreasing diameter opening into the interior thereof, the part ofgreater diameter of said recesses being in the direction of thedischarge path, the inner walls of said electrode being coated with anelectron-emitting material.

3. An electric discharge device comprising a container, a gaseousatmosphere therein, electrodes sealed therein, one of said electrodesbeing a hollow electrode having a contracted, tapering portion openinginto the interior thereof, the larger end of said contracted, taperingportion being in the direction of. the discharge path, the smaller endof said tapering portion being appreciably smaller in diameter thanthepart of said electrode into which said tapering portion opens, the innerwalls of said electrode being coated with electron emitting material.

4. An electric discharge device comprising a container, a gaseousatmosphere therein, electrodes sealed therein, one of said electrodesbeing an elongated, hollow electrode, the wall thereof facing thedischarge path being a re-entrant truncated cone opening into theinterior of said electrode, the end of greater diameter of said conebeing in the direction of the discharge path, and a coating of electronemitting material on the inner walls of said electrode.

GEORG GAIDIES. MARTIN REGER.

